We have studied smoking habit in the sample enrolled in the ten year follow-up of the "Pordenone Study on the Precursors of Atherosclerosis in Childhood". The response rate at ten year follow-up was very high (about 90%). Prevalence of smoking is 45.1% among males and 25.6% among females. Males and females aged 23 present a prevalence of smokers higher than the other groups while the group aged 26 smoke less. Males began to smoke at 16.4 years, females at 16.7. Mean daily consumption is 12.6 cigarettes among males, and 5.0 among females. Juvenile experimentation with cigarettes and juvenile smoking habit are strong predictors to smoke ten years later; while parental smoking behaviour is not so influential. Therefore we conclude that smoking habit acquired in youngs has a high probability to be maintained in adults, remarking the importance of planning a preventive intervention as early as possible.